Automatic cut-off for air-brake apparatus



No. 613,034. Patented Oct. 25, I898.

w. T. HAMILTON. AUTOMATIC BUT-OFF FOR AIB BRAKE APPARATUS.

(Application filed Apr. 1898.)

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NITED STATES PATENT ()FFIcE.

\VILLIAM T. HAMILTON, OF ALLEGHENY, PENNSYLVANIA.

AUTOMATIC CUT-OFF FOR AIR-BRAKE APPARATUS.

SPECIFICATION forming part of Letters Patent No. 613,034, dated October25, 1898.

' A li ati fli d April 1, 1898. Serial No. 676,082. (No model.)

To all whom it may concern:

Be it known that 1, WILLIAM T. HAMILTON, of Allegheny, in the county ofAllegheny and State of Pennsylvania, have invented a new and usefulImprovement in Automatic Cut- Offs for Air-Brake Apparatus, of which thefollowing is a full, clear, and exact description, reference being hadto the accompanying drawings, forming part of this specification, inwhich- Figure 1 shows in side view one of my improved devices applied tothe train-pipe of an air-brake apparatus. Fig. 2 is a vertical sectionof the device on a larger scale, showing part of the device inelevation. Fig. 3 is a horizontal section on the line III III of Fig. 2.

The main objects of my invention are twofold- -namely, first, to providemeans whereby, upon the breaking of a train equipped with an automaticair-brake system or on the bursting of a hose thereon, the engineman maybe able from the engine to release the air-brakes on the part of thetrain next to the engine without need of sending a man to close theangle-cock on the last car next to the place of separation of the trainor bursting of the hose, as heretofore, and, second, to prevent theengineman from inadvertently, by repeatedly setting and releasing thebrakes, reducing the air-pressure in the reservoirs to such extent as tobe incapable of further setting the brakes.

The first object isimportant in preventing possibility of accidents,because when, for instance, a train equipped with air-brake apparatus ofordinary construction breaks in two the brakes on both parts of thetrain are immediatelyset automatically, and as the anglecock at the rearend of the forward section is open the brakes cannot be released untilthat cock is closed by hand; but, and especially when such event occurson a downgrade, the rear section of a train may by partial release ofits brakes continue to advance and may collide with the front section,the engineman being unable to get it out of the way. When my improvementis applied to a train, it enables the engineman at once upon thebreaking intwo of the train to release the brakes, and thus to resumecontrol of the train and to draw the front section, if necessary,forwardout of the way of the pursuing rear section. In like manner if theair-hose should burst within a few cars of the rear of the train,although such bursting would immediately set the brakes, my improvement,by

enabling the engineman to release the brakes in the forward section ofthe train, will make itpossible for him to draw the whole train forward,as may be necessary in order to escape a train which may be following inthe rear.

The second object of my invention is also of importance, becauseitsometimes happens that in stopping a train or controlling its speed theengineman may repeatedly and at close intervals set and release thebrakes, so that eventually and unexpectedly to him the air-pressuremaybe reduced to such an extent as to be no longer sufficient to set thebrakes and stop the train. If this should happen on a downgrade, thetrain may get out of control of the engineman, and by running away maydo serious damage before sufficient pressure can be restored by theairpumps to put the train again under control. My improvement makes thisimpossible, for when the pressure of air in the reservoirs has beenreduced below a predetermined safety-point it will automatically preventthe engineman after setting the brakes from releasing them until thepumps have restored sufficient air-pressure to the main reservoirs toenable the brakes to be set again after they have been released. Myimprovement is therefore a safety apparatus of very great value in theprevention of accident from this and like causes.

In the drawings, 2 represents the trainpipe of an air-brake systemapplied to a car. At each end of the car, in the train-pipe, isinterposed one of my automatic valves 3 011 the inner side of theangle-cock 4. I show in Fig. 1 only one of these valves. The valve atthe other end of the car is similar in construction. Figs. 2 and 3illustrate what I deem to be the best form of construction of thisautomatic valve.

4 and 5 represent a pipe or passage within the valve-casing, having anintermediate partition 6, provided with a valve-port 7. The part 4:,which is next to the end of the car and to the angle-cock, I call theoutside passage, and the part 5, next to the middle of the car, I callthe inside passage. The valve-port 7 is controlled by a valve 8, whosestem 9 passes through stuffing-boxes in a cap 10 and is connected with apiston or diaphragm 11, which is set in a chamber 12 and is inwardlyactuated by a spring 13.

14 1 1 is a passage leading from the inside passage 5 to the chamber 12under the diaphragm, and 15 is a valve-port in said passage controlledby valve 16, operated by a piston or diaphragm 17 in a chamber 18, withwhich the parts of the passage 14 communicate. A spring 19 tends to urgethe valve 16 to its seat, and its pressure can be regulated byadjustment of a screw-cap 20. Connected with the outside passage 4 is avalve 16'; but as its ports, actuating-diaphragm, and spring and thematter of its connection with the under side of the diaphragm 11 aresimilar to the construction above described in connection with the valve16 it is unnecessary to repeat the same, and I have indicated them onthe drawings by the same reference-numerals, distinguishing them by theprime mark.

21 is a vent-passage which leads from the under side of the diaphragm 11to the outside passage 4, and 22 is a valve in said passage which isnormally seated toward the diaphragm 11 by a spring 23.

The manner in which the casing of the apparatus is preferably made inseveral parts and fitted together is sufficiently shown in the drawingswithout further description.

In adapting the apparatus for use in an airbrake system carryingordinarily, say, seventy pounds pressure in the train-pipe and auxiliaryreservoirs I adjust the spring of the valve 16 so that it will require,preferably, say, sixty pounds pressure on the under side of thediaphragm 17 to open said valve, and I adjust the springs of the valves8 and 16 so that they will require, preferably, say, thirty poundspressure on the under side of their diaphragms to open them and so theywill close when the pressure is less than that degree.

In the normal operation of the air-brake system the air-pressure beingexerted upon the diaphragm 17 will unseat the valve 16 and will admitthe air through the passage 14 14 to the under side of the diaphragm 11,and acting upon the valve 22 it will unseat said valve and permit theair-pressure to pass through the passage 21 into the passage 4, andacting upon the diaphragm 17 it will unseat the valve 16, thus admittingpressure through the passage 14: 14.. The air-pressure from the passagelet 14E acting on the under side of the diaphragm 11 will raise it andwill unseat the valve 8, opening the port 7, and said valve will remainunseated during the normal operation of the system. This action willtake place on all the cars on the train, the angle-cock at the rear endof the train being of course closed. If now the train should break intwo and should part the hose 2 1 at the left of the apparatus shown inthe drawings, the reduction of pressure caused thereby in the train-pipewould immediately set the brakes in both sections of the train and allthe valves 8 would immediately close. The main reservoir and air-pump onthe engine would, however, instantly restore the pressure in thetrain-pipe, and when that pressure reached sixty pounds it would actupon the diaphragm 17 of each of the valve apparatus in that section ofthe train and would successively open all the valves 8 there of exceptthe one next to the end of the last calgwhich would remain closedbecause of the vent-passage 21 permitting the free escape of air fromthe chamber under the diaphragm 11 past the valve 22, and thus reducingthe pressure in the train-pipe slightly below sixty pounds-that is,slightly below the pressure required to operate the valve 16. Suchrestoration of the pressure throughout the system would of courserelease the brakes. All the Valves 16 throughout the train would thenclose 5 but each of the valves 16 except the last would remain open,because operated at a lower air-pressure than that required to open thevalve 16, and would thus keep all the valves 8 open except the last ofthe train, because when the valve 16 is open the air from the train-pipehas free access to and can freely operate the actuating-diaphragm 11 ofthe main valve 8. The air brake system would thus be in operativeposition throughout the section of the train coupled to the engine, andthere would be sufficient air-pressure in the system to enable theengineman readily to control and set the brakes.

It will be seen that the operation of the apparatus as above describedis entirely automatic and reliable and that it will not in any wayinterfere with the reduction of the pressure in ordinary service stops.

If, in controlling a train equipped with airbrake apparatus providedwith my improvement, the engineman, by repeated setting and releasing ofthe brakes, should reduce the airpressure in the train-pipe, andauxiliary and main reservoirs, to less than thirty pounds, or thepressure for which the valve 16 is set, the springs 19 will immediatelyclose said valves, and the valve 16 having already been closed by thereduction of pressure below sixty pounds, all pressure will be cut offfrom the diaphragm 11, and the valve 8 will close, the valve 22 actingto prevent pressure from reaching the diaphragm through the vent-passage21. Such closing of the valves 8 will occur throughout the train andwill prevent the engineman from releasing the brakes until theair-pressure from the main reservoir into the pipe has been restored tomore than sixty pounds, whereupon the brake will be released and theauxiliary reservoirs recharged. In

the meantime the thirty pounds pressure in the brake-cylindersthroughout the system will be quite adequate to keep the brakes set.

One of these automatic cut-off valves is placed upon the tank of theengine or at some point between the tank and the first car. In this casethe sixty-pound regulating-valve is next to the tank and cannot beraised until that amount of pressure has .been stored up in the mainreservoir. It is evident that this arrangement is necessary, as a breakmight occur between the first car and the engine, and if the engine werenot provided with an automatic cut-off valve it would be impossible forthe engineer to jump up and release the/brakes and get away from theremainder of the train.

The apparatus thus operated is an effective safety device for thepurpose above described.

It is evident that the adjustment of the different valves may be variedto suit different conditions of use and that within the prin ciple of myinvention as defined in the claims the apparatus may be modified invarious ways.

I believe that I am the first to employ an automatic cut-off valve whichwill close on the reduction of the air-pressure below a certain pointand the first also to employ such valve with controlled air-inlets toadmit air for opening the same with mechanism adapted to open one inletat a lower pressure than that at which the other will open, so that thevalve when opened by pressure through the high-pressure inlet can beheld open by pressure acting through the low-pressure inlet.

I claim 1. In air-brake apparatus, a cut-off valve connected with thetrain-pipe, and means independent of said cut-0E valve adaptedautomatically to open and close said valve on the variance of pressurebeyond a certain point; substantially as described.

2. In air-brake apparatus,an automatic cutoff valve, connected with atrain-pipe, means set to operate conjointly with and to control themovement of said automatic cut-0E valve, said parts being held open byapredeternlined pressure, any abnormal reduction in said pressurecausing these parts to completely close the train-pipe until thepredetermined pressure is restored.

3. In air-brake apparatus, acut-off valve connected with the train-pipe,and means set automatically to open said valve bya certain pressure inthe train-pipe, and other means set to open the same by lesspressure,whereby when the valve has been opened by the one it can beheld open by the other; substantially as described.

4. In air-brake apparatus, a cut-oil": valve connected with thetrain-pipe, and adapted to be moved by the air-pressure and air-inletsadapted to admit air for moving the same, and mechanism controlling theinlets, one inlet being adapted to open at a lower pressure than that atwhich the other will open,whereby when the valve has been opened bypressure through the high-pressure inlet, it can be held open bypressure acting through the other inlet; substantially as described.

5. In air-brake apparatus, the combination with the train-pipe, of acut-0E valve at each end of the car, air-operated mechanism adapted tomove the cut-off valve, inlet-ports on the outside and inside of thecut-off valve respectively, and mechanism adapted to control saidinlet-ports and to permit the passage of air therethrough at differentpressures; substantially as described.

6. In air-brake apparatus, the combination of a cut-off valve, itsactuating-diaphragm, ports leading to said diaphragm from opposite sidesof the cut-off valve, high and low pressure valves controlling saidports respectively, said valves having springs by which they may beadjusted to operate at certain pressures, and a vent-passage and valve;substantially as described. 7

In testimony whereof I have hereunto set my hand.

.VVILLIAM T. HAMILTON.

Witnesses:

THOMAS W. BAKEWELL, GEORGE B. BLEMMING.

